1999 Mercury Mountaineer Ignition Lock Cylinder Replacement Cost

The ignition lock cylinder and ignition switch are two separate components. The lock cylinder is the portion that the key slides into and allows the ignition to turn. This is one of your vehicle's defenses against theft.

If the correct key is inserted, small actuators on the lock cylinder will allow it and ignition switch to rotate. 

When the ignition switch lock cylinder fails, it can create a situation where the ignition cannot be turned, or takes much wiggling and shaking before it finally turns. Or, it's possible the ignition will turn and run with the key removed, or lets the key be removed in any position. Lastly, the lock can fail to release your key, or not allow the key to travel all the way into the ignition lock cylinder.

When the ignition lock cylinder is malfunctioning, it may be impossible to insert the key, turn the ignition, or remove the key from the ignition. If the key won't go in or turn, you won't be able to drive the car, obviously. If the key won't come out, theft is a major concern. Either way, you'll want this fixed quickly.

Theres no set maintenance routine for the ignition lock cylinder. Lock cylinders fail somewhat commonly, but mostly for higher-mileage vehicles. Most vehicles will never need the lock cylinder replaced. You can help yours last by cleaning your ignition key, making sure there's no lint on it before putting it in the ignition, and keeping your keychain fairly light, so as not to put added pressure on the cylinder while you drive.